en: An episode is declared when the ozone reaches .20 parts per million parts of air for one hour . A Stage 1 episode is declared when ozone levels reach 0.20 parts per million .
ms: Satu episod diisytiharkan apabila ozon mencapai.20 bahagian per juta bahagian udara selama satu jam. Episod Tahap 1 diisytiharkan apabila tahap ozon mencapai 0.20 bahagian per juta.